Core for steel castings



the following is a specification.

Patented Sept. 15, 1925.

UNITED STATES PATENT OFFlCiE.

cm rs. ncmr, or samaucx, GERMANY, assrcnoa 'ro mom's, OPPEL'I 4: cm, onsmmscnm m snscmmrrna HAFTUNG, or saannaucx, seam, a

In Drawing.

To all whom it may concern:

Be it known that I, CARL FRIEDRICH Eomm'r, a citizen of the Republic of Germany, residing at Saarbruck, Germany, have invented certain new and useful.Improve-' ments in for Steel Castings, of which The invention relates-to improved cores for smooth steel castings and more particularly for hollow steel castings such; as ingot moulds, valve seatings, pumpcaslngs and the like. It is well known that the removal of the core from such castings offers considerable difiiculties, as the mass from which the core is made and which consists of chamot, quartzite sand and the like is foun to have caked or baked. The removal of such cores from the castin can as a rule onl be effected by the ai of pneumatic too which involves increased wa s for cleaning the castings. It has' there ore already been sug to obtain smooth castings by employing a special mould and core mass, the latter consistingemntially of ordinary sand with an admixture of loam or of 'gy ,um and fats or fatty oils or the like. or the manufacture of ordinary grey castings these coresare quite suitable, as grey iron is cast 'at a temperature of 14001500 according to quality. This 'mould and core mass can, however, not be employed for steel castings for the following reasons: owing to the high temperature of the molten steel, which lies between 17001800, the upper layer of the core melts at the moment when the steel is cast into the mould and sticks to the casting, formin a rough surface and a art of the core ba es together, owing to its ow refractoriness, as even the best quartz sand already jsinters at a temperature of 1600.

This invention, consists of a core for steel castings in which the above named drawbacks and avoided. y

The improved core consists either of an upper layer or entirelyof aluminum-nitride oraluimii'" -nitride containing substances with the usual binding agents, for instance molasses, tar and'the l1ke The core manufactured inthis manner has the advanta that owing to its high refractoriness t e core material does not burn to the casting and that the core after the casting or after the burning of the binding disadvantages are effectively CORE FOR STEEL CASTING5.

Application filed November 14, 1922. Serial No. 600,954.

material does not cake at all and can be removed fromthe casting by the simplest tools or even by hand, as practical use has shown, without the least effort. From the hygiemc polnt of view this must also be considered of the greatest im ortance for the workmen engaged in cleaning the cast- %xperience has shown that the saving in wages for the cleaning of castings amounts to about A further advantage resides in the fact that the material of the improved core owin to its high refractoriness may be employe The advantages obtained by the employment of calcined clay consist in the greater firmness of the core, greater porosity and consequent easier escape of the gases and easier removal of the core from the casting, than in the first described core.

What I claim as my invention and desire to secure by Letters Patent is:

1. As a new article of manufacture, the improved core for producing hollow steel castings, consisting of an ordinary core covered with a coating containing aluminumnitride mixed with a suitable binder.

2. As a new article of manufacture, the improved core-for producing hollow steel castings, consistin of aluminum-nitride mixed with a suita le binder.

3. As a new article of manufacture, the improved core for producing hollow steel castings, consisting of an.0r .i ary core coated with aluminum-nitride and calcined clay with. a suitable binder.

4. As a new article of manufacture, the improved core for producing hollow steel castings, consisting of a mass of material containing aluminum-nitride, and a suitable binder.

5. The process for producing cores for steel castings, which consist in mixing a coating containing aluminum-nitride with a suitable binding agent and covering an ordinary core with said coatin 6. The process for prosucing cores for 5 steel castings, which consists in mixing aluminum-nitride with a suitable binding agent and moulding the core thereof.

7. The process for producing cores for steel castings, which consists in preparing 10 a mixture of aluminum-nitride, calcined clay and a suitable binding agent and coating an ordinary core therewith.-

8. The process for producing cores for steel castin s, which consists in preparing a mixture 0 aluminum-nitride, calcined clay I and a suitable binding agent and moulding the core thereof.

In testimony whereof I aifix my signature.

' ABL FR. ECKERT. 

